Head-up displays are ever more frequently installed in modern motor vehicles, thus display devices having an imaging projection device to project a virtual image, thus a graphical information, in a beam path onto a reflection surface in an internal space of the motor vehicle (normally onto a windshield).
The head-up display is thereby often positioned in an installation space in front of the driver. The head-up display is comprised of a plurality of individual mechanical, optical and electronic components. In order to deflect the virtual image of the imaging projection device out of the internal space of a housing onto the reflection surface, mirrors are installed within the housing, which mirrors must be adjusted depending on a vehicle type and a windshield variant.
From DE 27 47 760, an optical display device is known that uses an acrylic block as a collimation mirror. A head-up display that uses a wedge-shaped glass body to deflect light of a projector is known from GB 2 163 869 A. The glass body is thereby arranged within a housing in which a projector is also mounted. US 2005/0259034 A1 describes an additional head-up display that has two flat mirrors installed within the housing.
However, the manufacturing and installation of the internal mirrors especially is very complicated and must take place while complying with tight tolerances. The attachment of mirrors in the housing incurs a high installation expenditure, additional. weight and costs due to the installation of additional retainers. The high installation expenditure is predominantly due to the fact that the mounting of the mirror must be adjusted exactly to the corresponding vehicle model in order to direct a projection of a digital display content onto the windshield. Given too high a load on the mirror mounts due to shaking, the mirrors begin to vibrate, whereby their optical quality degrades.